Eye tracking and reaction-time testing both indicated attention toward methamphetamine-related pictures in a small study of men with a history of use. These measurements captured allocation of attention to cues; they were not tests for identifying methamphetamine in the body.
Mirtorabi and colleagues compared 30 men who used methamphetamine with 36 male controls reporting no prior drug use. On average, about 20 days had elapsed since the clinical group’s last methamphetamine use. Participants viewed paired drug-related and neutral pictures while their gaze was recorded. A dot then appeared in one location, and response time supplied an indirect measure of attention.
In the methamphetamine group, initial fixations on drug cues lasted longer than those on neutral pictures, and a greater proportion of viewing time was directed toward drug cues. First fixations also landed on cue pictures more often than chance. Controls did not show a significant first-fixation preference for cues. The within-person drug-versus-neutral comparison is important; the result is more specific than simply saying that users looked longer overall.
The methamphetamine group responded faster when the probe replaced a drug-related picture, whereas that probe-location comparison was nonsignificant in controls. Self-reported craving rose after the task, from a mean of 2.80 to 4.23 on the study’s rating scale. Because cue exposure and the task occurred together, that before-and-after change does not isolate every possible reason craving increased.
The sample was small and all male, and the study did not randomly assign long-term methamphetamine exposure. Attention bias can vary with stimuli, context and recovery stage. The investigators did not validate a cutoff that classifies current intoxication, predicts relapse or determines driving impairment in an individual. Eye position, a button response and a chemical analysis of blood or urine are different measurements; evidence that one is sensitive to drug cues does not make it a substitute for the others.
See how cue-induced craving can differ from background craving for a complementary study.